Measurement of GABA and other neuroactive compounds in CSF to determine the extent to which these measurements reflect alterations of brain levels during mental disorders. Specifically to study: (1) the relationship between brain and CSF levels of GABA, amino acids and other related substances of neurochemical interest, i.e., dopamine, norepinephrine, serotonin, and their metabolic products using appropriate animals to compare the influence of various drug and surgical treatments on the relative levels of the compounds in the CSF and specific areas of the brain. These studies are intended to determine the extent to which analyses of CSF can be beneficial in the diagnosis, treatment and understanding of various mental and neurological disorders. (2) to measure the levels of GABA as well as the other components, in CSF of patients with various mental or neurological disorders. These patient studies have been set up, in collaboration with investigators from NINCDS and NIMH to measure the levels relative to that of normal individuals, and also to study the influence of the various treatments on these components.